JPH09192804A - Production of extra-low carbon cold-rolled steel sheet - Google Patents
Production of extra-low carbon cold-rolled steel sheetInfo
- Publication number
- JPH09192804A JPH09192804A JP8007771A JP777196A JPH09192804A JP H09192804 A JPH09192804 A JP H09192804A JP 8007771 A JP8007771 A JP 8007771A JP 777196 A JP777196 A JP 777196A JP H09192804 A JPH09192804 A JP H09192804A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- steel sheet
- nozzle
- cold
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/108—Feeding additives, powders, or the like
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/0025—Charging or loading melting furnaces with material in the solid state
- F27D3/0026—Introducing additives into the melt
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、極低炭素冷延鋼
板の製造方法に関するものであって、アルミキルド溶鋼
の連続鋳造時に起こるタンディッシュの上ノズル、スラ
イディングノズルや浸漬ノズル（以下、単に「ノズル」
と総称する）内面へのAl2O3 の付着によるノズル閉塞を
防止し、かつ、アルミキルドでは不可避的に発生するAl
2O3 クラスターを起因とする鋳片の表面欠陥、および冷
延板のAl2O3 起因の欠陥を防止する有効な技術に関して
の提案である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an extremely low carbon cold-rolled steel sheet, which comprises an upper nozzle, a sliding nozzle, a dipping nozzle (hereinafter simply referred to as "nozzle", which occurs during continuous casting of molten aluminum killed steel. "
Al) that prevents nozzle clogging due to adhesion of Al 2 O 3 on the inner surface and that is unavoidable with aluminum killed
This is a proposal regarding an effective technique for preventing the surface defects of the slab caused by 2 O 3 clusters and the defects caused by Al 2 O 3 in the cold-rolled sheet.
【０００２】[0002]
【従来の技術】従来、極低炭素冷延鋼板を製造に当たっ
ては、溶製時に鋼中のＣおよびＮを析出固定するTiおよ
びNbの歩留りを高めるため、さらには連続鋳造において
鋳片表面に発生するブローホールを防止するために、脱
炭処理後の溶鋼中にAlを添加して、溶鋼中の溶存酸素濃
度を低下させるのが通例である。2. Description of the Related Art Conventionally, in manufacturing an extremely low carbon cold-rolled steel sheet, in order to increase the yield of Ti and Nb which precipitate and fix C and N in the steel during melting, it is further generated on the surface of the slab in continuous casting. In order to prevent such blowholes, it is customary to add Al to the molten steel after decarburization to reduce the dissolved oxygen concentration in the molten steel.
【０００３】このような処理をしたアルミキルド鋼を連
続鋳造すると、脱酸時に生成したAl 2O3 系の酸化物がタ
ンディッシュのノズル内壁に付着し、ノズルを閉塞する
ことにより溶鋼流路が狭められ、所望の溶鋼流量が得ら
れなくなるという問題がある他、ノズル内壁に付着した
Al2O3 の一部がはがれ、それが鋳型内の凝固シェルに捕
捉されて鋳片表面の欠陥となるという問題もあった。Aluminum-killed steel treated in this way is continuously used.
When continuously cast, Al generated during deoxidation TwoOThreeThe oxide of the system is
It adheres to the inner wall of the nozzle of the dish and blocks the nozzle.
This narrows the molten steel flow path to obtain the desired molten steel flow rate.
In addition to the problem that it will not be attached, it adhered to the inner wall of the nozzle
AlTwoOThreePart of it was peeled off and trapped in the solidification shell in the mold.
There is also a problem in that the surface of the cast piece is caught and becomes a defect.
【０００４】このような問題点に対しては従来、タンデ
ィッシュのノズルからAr等の不活性ガス吹き込みを行
い、Al2O3 系の酸化物のノズル内壁への付着を防止する
方法で対処していた。しかしながら、この方法は、吹き
込んだ不活性ガスが鋳型内の凝固シェルに捕捉され、鋳
片の気泡性欠陥となるという新たな問題を招いた。Conventionally, such a problem is dealt with by a method of blowing an inert gas such as Ar from a tundish nozzle so as to prevent Al 2 O 3 -based oxide from adhering to the inner wall of the nozzle. Was there. However, this method causes a new problem that the blown-in inert gas is trapped by the solidified shell in the mold and becomes a bubble defect of the cast piece.
【０００５】その他、溶鋼中にCaあるいはCa−Si等のCa
合金を添加し、Al2O3 系介在物を低融点のCaO-Al2O3 系
介在物とし、ノズル内壁へのAl2O3 の凝集付着を抑制す
る従来技術があった。例えば、 特開昭58−154447号公報には、取鍋内の溶鋼にCa：
0.2 〜0.5 kg／ｔを添加してAl2O3 系介在物の低融点化
をはかり、融化したAl2O3 をCaO-Al2O3 の形として溶鋼
表面に浮上させ、これを取鍋内から除去する方法が開示
されている。 特開昭61−276756号公報には、アルミキルド溶鋼中
に、溶製段階もしくは連続鋳造時にCaまたはCa合金を添
加することにより、鋼中に２〜40ppm のCaを残留させて
CaO-Al2O3 系介在物を生成させる方法が、開示されてい
る。[0005] In addition, Ca such as Ca or Ca-Si is contained in molten steel.
There is a conventional technique in which an alloy is added and an Al 2 O 3 -based inclusion is changed to a CaO-Al 2 O 3 -based inclusion having a low melting point to suppress the aggregation and adhesion of Al 2 O 3 on the inner wall of a nozzle. For example, in JP-A-58-154447, molten steel in a ladle contains Ca:
0.2 to 0.5 kg / t was added to measure the low melting point of the Al 2 O 3 inclusions, is floated on the molten steel surface Al 2 O 3 was infusible in the form of CaO-Al 2 O 3, ladle it A method of removing from within is disclosed. Japanese Patent Laid-Open No. 61-276756 discloses that by adding Ca or a Ca alloy to molten aluminum killed steel at the melting stage or continuous casting, 2-40 ppm of Ca remains in the steel.
Method of forming a CaO-Al 2 O 3 based inclusions is disclosed.
【０００６】ところが、CaあるいはCa−Si等のCa合金を
添加する上記の各方法は、鋼中に添加されたCaがCaS お
よびCaO となり、鋼板における錆の発生起点となる問題
があり、特に鋼材での全Ca量が10ppm 以上になると、発
錆が著しくなる。しかもこれらの技術にあっては、Al脱
酸時に生成したAl2O3 が、その後タンディッシュや鋳型
内において浮上分離できずに凝集してクラスター化する
ことにより、鋳片内で大型の介在物となり、これが鋳片
の表層部に捕捉されて冷延板でヘゲ等の表面欠陥となる
という問題点もあった。However, in each of the above methods of adding Ca or a Ca alloy such as Ca-Si, there is a problem that Ca added to the steel becomes CaS and CaO, which is a starting point of rust generation in the steel sheet. When the total amount of Ca at 10ppm or more, rusting becomes remarkable. Moreover, in these technologies, Al 2 O 3 generated during deoxidation of Al cannot be floated and separated in the tundish or the mold, and aggregates and clusters, resulting in large inclusions in the slab. There is also a problem that this is captured by the surface layer of the slab and becomes a surface defect such as a whip in the cold rolled sheet.
【０００７】[0007]
【発明が解決しようとする課題】そこで、本発明の目的
は、Ti含有アルミキルド鋼の連続鋳造におけるノズル閉
塞がなく、しかも鋳片表面欠陥のない極低炭素冷延鋼板
の有効な製造方法を提案することにある。また、本発明
の他の目的は、鋼中の酸化物系介在物種を調整すること
によって、連続鋳造時におけるタンディッシュノズル閉
塞および鋳片の表面欠陥を防止すると共に、冷延鋼板を
700 ℃〜Ａc3点の温度域で連続焼鈍することによって、
深絞り性に優れる冷延鋼板を製造することにある。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose an effective method for producing an ultra-low carbon cold-rolled steel sheet which is free from nozzle blockage and has no slab surface defect in the continuous casting of Ti-containing aluminum killed steel. To do. Moreover, another object of the present invention is to prevent clogging of the tundish nozzle during continuous casting and surface defects of the slab by adjusting the type of oxide inclusions in the steel,
By continuous annealing in the temperature range of 700 ℃ ~ A c3 point,
It is to produce a cold rolled steel sheet having excellent deep drawability.
【０００８】[0008]
【課題を解決するための手段】上掲の目的は、下記に示
す要旨構成にかかる製造方法の採用によって達成するこ
とができる。 (1) Ｃ≦0.005 wt％, Mn≦1.0 wt％を含有する脱炭処理
後の溶鋼中に、Alおよび／またはSiを添加することによ
り、該溶鋼中の酸素濃度を10〜200 ppm にした半脱酸溶
鋼とし、この溶鋼中に、含Ti物質を添加してさらに脱酸
し、Al≦0.005 wt％、Si≦0.20wt％、Ti：0.01〜0.10wt
％を含有する溶鋼とすると共に、該溶鋼中の介在物の主
成分をTiとAlとの複合酸化物、TiとSiとの複合酸化物、
もしくはTi, AlおよびSiの複合酸化物とした溶鋼を溶製
し、次いでこの溶鋼を連続鋳造し、その後、熱間圧延お
よび冷間圧延を経たのち、得られた冷延鋼板を 700℃〜
Ａc3点の温度域で連続焼鈍することを特徴とする極低炭
素冷延鋼板の製造方法。The above object can be achieved by adopting a manufacturing method according to the following constitution. (1) By adding Al and / or Si to the decarburized molten steel containing C ≦ 0.005 wt% and Mn ≦ 1.0 wt%, the oxygen concentration in the molten steel was adjusted to 10 to 200 ppm. A semi-deoxidized molten steel is added, and a Ti-containing substance is added to this molten steel to further deoxidize it. Al ≤ 0.005 wt%, Si ≤ 0.20 wt%, Ti: 0.01 to 0.10 wt
%, And the main component of inclusions in the molten steel is a complex oxide of Ti and Al, a complex oxide of Ti and Si,
Alternatively, molten steel made of a composite oxide of Ti, Al and Si is smelted, then this molten steel is continuously cast, and then hot-rolled and cold-rolled.
A method for producing an ultra-low carbon cold-rolled steel sheet, which comprises performing continuous annealing in a temperature range of Ac 3 points.
【０００９】[0009]
【発明の実施の形態】極低炭素冷延鋼板の製造に当たっ
ては、まず溶製段階の処理として、転炉から取鍋に出鋼
した溶鋼のMn含有量を1.0 wt％以下に調整した後、真空
処理によりＣ：0.005 wt％以下の極低炭素域に成分調整
することから始まる。BEST MODE FOR CARRYING OUT THE INVENTION In manufacturing an ultra-low carbon cold-rolled steel sheet, first, as a treatment in a melting stage, after adjusting the Mn content of molten steel discharged from a converter to a ladle to 1.0 wt% or less, It begins by adjusting the composition to an extremely low carbon region of C: 0.005 wt% or less by vacuum treatment.
【００１０】すなわち、Mnは材質強化成分として、好ま
しくは 0.05 wt％以上は添加するが、過剰の添加は耐２
次加工性、化成処理性および脱炭処理を阻害するため、
1.0wt％以下とする。また、Ｃは、その含有量が0.005 w
t％をこえると、再結晶温度が上昇すると共に、伸び(E
l)の低下、深絞り性（ｒ値）の低下の不利を招くため、
0.005 wt％以下に制限する。なお、残部は鉄および不可
避不純物の組成になり、不可避不純物として、Ｐおよび
Ｓを、それぞれ0.030 wt％以下および0.020 wt％以下に
抑制する。That is, Mn is added as a material-strengthening component, preferably in an amount of 0.05 wt% or more.
In order to prevent secondary workability, chemical conversion treatment and decarburization treatment,
1.0 wt% or less. The content of C is 0.005 w.
When it exceeds t%, the recrystallization temperature rises and the elongation (E
l) and deep drawability (r value) are disadvantageous.
Limit to 0.005 wt% or less. The balance is composed of iron and unavoidable impurities, and P and S as unavoidable impurities are suppressed to 0.030 wt% or less and 0.020 wt% or less, respectively.
【００１１】さて、上記のように極低炭素域まで脱炭す
ると、溶鋼中の溶存酸素濃度は数100ppmと非常に高くな
るため、従来は、0.010 wt％以上のAlを添加することに
より溶存酸素を低減していた。この脱酸処理ではAl酸化
物（Al2O3)が生成するが、生成したAl2O3 のうち浮上分
離できなかったAl2O3 が、また、溶鋼が再酸化した時に
生成するAl2O3 が、連続鋳造においてタンディッシュの
ノズル閉塞を招き、また、クラスター化し、数100 μｍ
の大きさとなるため、鋳片表面の欠陥となったり、冷延
板でのヘゲ等の表面欠陥の原因となることは、上述した
とおりである。When decarburizing to the extremely low carbon range as described above, the concentration of dissolved oxygen in molten steel becomes as high as several 100 ppm, so conventionally, dissolved oxygen was added by adding 0.010 wt% or more of Al. Was being reduced. The Al oxide is deoxidized (Al 2 O 3) is to produce, but Al 2 O 3 was not able flotation of the resulting Al 2 O 3, also produced when the molten steel is re-oxidized Al 2 O 3 causes clogging of the tundish nozzle in continuous casting, and clusters to several hundred μm
As described above, it causes defects on the surface of the slab and causes surface defects such as shaving on the cold rolled sheet.
【００１２】そこで、本発明では、上記の問題を誘発す
るAl2O3 の生成を抑制するために、溶鋼中のAl量を低下
させることにより、介在物の形態を、従来のAl酸化物
（Al2O 3)から、TiとAlとの複合酸化物、TiとSiとの複合
酸化物、もしくはTi, AlおよびSiの複合酸化物とするこ
と( 望ましくはTi酸化物＝30〜95wt％, Al2O3≦30wt％
とすること）にした。Therefore, the present invention induces the above problems.
AlTwoOThreeDecrease the amount of Al in molten steel to suppress the formation of
By changing the form of inclusions to the conventional Al oxide.
(AlTwoO Three), A complex oxide of Ti and Al, a complex oxide of Ti and Si
Oxide or a composite oxide of Ti, Al and Si.
And (preferably Ti oxide = 30-95wt%, AlTwoOThree≤30wt%
I decided to).
【００１３】介在物の形態を上記のようにすると、Al2O
3 クラスターの発生を防ぎ、かつタンディッシュのノズ
ル閉塞および冷延鋼板の表面欠陥の発生を抑えることが
できるようになる。発明者らの研究によると、溶鋼中の
Al濃度は0.005 wt％を超えると、介在物中のAl酸化物濃
度は30wt％を超える。その結果、介在物はクラスター化
しやすくなり、100 μｍ以上に巨大化し、スラブの表面
欠陥, 冷延鋼板での欠陥になるとともに、ノズルの内壁
に付着しやすく、ノズル閉塞しやすいことがわかった。When the morphology of inclusions is as described above, Al 2 O
It is possible to prevent the formation of 3 clusters and to suppress the nozzle clogging of the tundish and the surface defects of the cold rolled steel sheet. According to the research by the inventors,
When the Al concentration exceeds 0.005 wt%, the Al oxide concentration in the inclusions exceeds 30 wt%. As a result, it was found that the inclusions tended to cluster, became larger than 100 μm and became surface defects of the slab, defects in the cold-rolled steel sheet, and easily adhered to the inner wall of the nozzle, resulting in clogging of the nozzle.
【００１４】このような知見に基づき本発明では、溶鋼
中へのAl添加量を抑えて0.005 wt％以下添加して溶存酸
素濃度の低下を図る。一方で不足分はTi含有合金を添加
してTi脱酸することにより、前記溶存酸素量のさらなる
低減を図る。このことによって介在物の主成分はTi−Al
の複合酸化物となる。従って、その介在物は巨大なクラ
スターに成長することはなく、スラブの表面欠陥や冷延
鋼板での欠陥を招くことがなくなる。しかも、ノズル閉
塞の防止を実現することができる。また、本発明は、上
記のTi脱酸前にSiを添加する。このことにより、介在物
は、TiとSiとの複合酸化物、Ti, AlおよびSiの複合酸化
物となり、介在物のクラスター化による巨大化、ノズル
の閉塞はより一層緩和される。Based on such knowledge, in the present invention, the amount of Al added to molten steel is suppressed and 0.005 wt% or less is added to reduce the dissolved oxygen concentration. On the other hand, for the shortage, Ti-containing alloy is added to deoxidize Ti to further reduce the amount of dissolved oxygen. As a result, the main component of inclusions is Ti-Al.
It becomes a complex oxide of. Therefore, the inclusions do not grow into huge clusters, and the surface defects of the slab and the defects in the cold rolled steel sheet are not caused. Moreover, it is possible to prevent the nozzle from being blocked. Further, in the present invention, Si is added before the Ti deoxidation. As a result, the inclusions become a composite oxide of Ti and Si, or a composite oxide of Ti, Al, and Si, and the enlargement of the inclusions due to clustering and clogging of the nozzle are further alleviated.
【００１５】なお、本発明において、形成される介在物
の組成は、Ti酸化物＝30〜95wt％、Al2O3 ≦30wt％の組
成のものが望ましい。それは、Al2O3 が30wt％を超える
と巨大クラスター化しやすいからである。また、Ti酸化
物も95wt％を超えるとクラスター化し易い傾向がある。
ただし、Ti酸化物濃度が30wt％未満では、Tiの脱酸力が
弱く、溶鋼中の酸素濃度が高くなり、冷延鋼板での表面
品質に悪影響を及ぼすので、Ti酸化物濃度は30wt％以上
とすることが望ましい。In the present invention, the composition of the inclusions formed is preferably such that Ti oxide = 30 to 95 wt%, Al 2 O 3 ≦ 30 wt%. This is because if Al 2 O 3 exceeds 30 wt%, it becomes easy to form huge clusters. Further, when the Ti oxide also exceeds 95 wt%, it tends to be clustered.
However, if the Ti oxide concentration is less than 30 wt%, the deoxidizing power of Ti will be weak and the oxygen concentration in the molten steel will be high, which will adversely affect the surface quality of the cold rolled steel sheet. Is desirable.
【００１６】溶鋼中のAl量とタンディッシュのノズル内
壁へのAl2O3 の付着量との関係を図１に、また溶鋼中の
Al量とAl2O3 クラスターに起因した冷延鋼板での表面欠
陥の発生量を図２に、それぞれ示す。なお、Al2O3 の付
着量および表面欠陥の発生量は、ノズルへのAl2O3 の付
着厚み、コイル長さ当たりの欠陥個数の指数として表示
した。図１および２から、Al量を0.005 wt％以下にする
ことによって、ノズル閉塞、そして冷延鋼板での表面欠
陥が大きく減少することがわかる。The relationship between the amount of Al in molten steel and the amount of Al 2 O 3 deposited on the inner wall of the tundish nozzle is shown in FIG.
FIG. 2 shows the amount of surface defects generated in the cold rolled steel sheet due to the amount of Al and the Al 2 O 3 cluster, respectively. The amount of Al 2 O 3 adhered and the amount of surface defects generated were indicated as an index of the thickness of Al 2 O 3 adhered to the nozzle and the number of defects per coil length. From FIGS. 1 and 2, it can be seen that nozzle clogging and surface defects in the cold rolled steel sheet are greatly reduced by setting the Al content to 0.005 wt% or less.
【００１７】上述の処理において、Al添加量の低減は脱
酸不足を招いて溶鋼中の溶存酸素量が増加し、連続鋳造
時に鋳片の表面にブローホールが発生する原因となる。
そこで、本発明では、ブローホールの発生を防止するた
めに、Tiを添加することとしたのである。ここで、溶鋼
中のTi量と連続鋳造鋳片の表層部のブローホールの発生
個数との関係を、上記と同様に指数を用いて図３に示
す。同図に示すように、溶鋼中のTi量を0.010 wt％以上
に調整することによって、ブローホールの発生個数は大
幅に減少し、冷延鋼板における表面品質の悪化を回避す
ることができる。In the above-mentioned treatment, the reduction of the amount of Al addition causes deoxidation deficiency and the amount of dissolved oxygen in the molten steel increases, which causes blowholes on the surface of the slab during continuous casting.
Therefore, in the present invention, Ti is added to prevent the generation of blow holes. Here, the relationship between the amount of Ti in the molten steel and the number of blow holes generated in the surface layer portion of the continuously cast slab is shown in FIG. 3 using the same index as above. As shown in the figure, by adjusting the amount of Ti in the molten steel to 0.010 wt% or more, the number of blowholes generated can be significantly reduced, and deterioration of the surface quality of the cold rolled steel sheet can be avoided.
【００１８】また、Tiで脱酸することにより、介在物の
巨大なクラスター化によるスラブ、冷延鋼板での表面欠
陥の防止、ノズル閉塞の防止に有効である一方、Ti添加
量が多すぎると、溶鋼中にTiＮが生成し、このTiＮがノ
ズルに付着し、ノズルを通しての空気酸化により、ノズ
ル内面にTi酸化物が生成する。これにより、ノズルの閉
塞が急激に進み問題が生じる。すなわち、図４に、溶鋼
中のTi量とタンディッシュのノズル内壁へのTiN および
Ti酸化物の付着量（指数）との関係を示すように、Ti量
が0.100 wt％をこえるとノズル閉塞が急激に進行するこ
とがわかる。従って、溶鋼中のTi量は、0.01〜0.10wt％
の範囲に調整する必要がある。Further, deoxidizing with Ti is effective for preventing slabs due to huge clustering of inclusions, surface defects in cold-rolled steel sheets, and preventing nozzle clogging. On the other hand, if the Ti addition amount is too large, , TiN is generated in the molten steel, the TiN adheres to the nozzle, and air oxidation through the nozzle generates Ti oxide on the inner surface of the nozzle. As a result, the nozzle is clogged rapidly, causing a problem. That is, in FIG. 4, the Ti content in the molten steel and the TiN on the inner wall of the tundish nozzle and
As shown by the relationship with the amount (index) of Ti oxide adhered, it is clear that nozzle clogging progresses rapidly when the Ti amount exceeds 0.100 wt%. Therefore, the amount of Ti in molten steel is 0.01 to 0.10 wt%
It is necessary to adjust to the range of.
【００１９】Ti合金量による脱酸に先立って、Al, Si含
有合金を添加するのは、上述の介在物組成を複合介在物
にすることの他に、Ti脱酸前の溶存酸素濃度を低下させ
る目的がある。脱炭処理後の溶鋼は、溶存酸素量が数10
0 ppm と多く、Tiによって脱酸を行うと、Tiの歩留りが
低下し、より多くのTiが必要となり、経済的に不利にな
るだけでなく、生成するTi酸化物量および脱酸後の酸素
濃度が高くなり、冷延鋼板での表面欠陥を悪化させる。
ここで、脱酸後のAl濃度、Si濃度については、望ましく
はAl≧0.001 wt％、または、Si≧0.01wt％が望ましい。
一方、Siの過剰添加は、冷延鋼板での材料特性を悪化す
るため、0.20wt％以下に制限する必要がある。すなわ
ち、溶鋼中のSi量と冷延鋼板での伸びとの関係を図５に
示すが、Si量を0.20wt％以下に制限することによって、
冷延鋼板での伸びの著しい低下を回避することができ
る。Prior to the deoxidation by the amount of Ti alloy, the addition of the alloy containing Al and Si is not only to make the above inclusion composition into a composite inclusion but also to reduce the dissolved oxygen concentration before Ti deoxidation. There is a purpose to let. The molten steel after decarburization has a dissolved oxygen content of several tens.
As much as 0 ppm, deoxidation with Ti lowers the yield of Ti and requires more Ti, which is not economically disadvantageous. In addition, the amount of Ti oxide produced and the oxygen concentration after deoxidation are high. Becomes higher, which aggravates surface defects in the cold rolled steel sheet.
Here, the Al concentration and the Si concentration after deoxidation are desirably Al ≧ 0.001 wt% or Si ≧ 0.01 wt%.
On the other hand, excessive addition of Si deteriorates the material properties of the cold rolled steel sheet, so it is necessary to limit it to 0.20 wt% or less. That is, the relationship between the amount of Si in the molten steel and the elongation in the cold-rolled steel sheet is shown in FIG. 5, but by limiting the amount of Si to 0.20 wt% or less,
It is possible to avoid a significant decrease in elongation of the cold rolled steel sheet.
【００２０】また、冷延鋼板におけるプレス成形性を向
上するには、溶鋼においてＣおよびＮを固定する必要が
ある。本発明で対象とする成分組成は低Al量の弱脱酸鋼
であるため、酸素との親和力の小さいNbでＣおよびＮを
固定することが有効となる。このNbの添加量は、0.030
wt％を超えると、NbＣ等の析出物が増加して細粒化し、
伸び（El）や絞り（ｒ値）が劣化し、経済的にも不利に
なるため、0.030 wt％を上限として添加する。Further, in order to improve the press formability of the cold rolled steel sheet, it is necessary to fix C and N in the molten steel. Since the component composition targeted by the present invention is a weakly deoxidized steel with a low Al content, it is effective to fix C and N with Nb having a small affinity with oxygen. The amount of Nb added is 0.030.
If it exceeds wt%, precipitates such as NbC increase and become finer particles,
Since elongation (El) and drawing (r value) deteriorate and it is economically disadvantageous, 0.030 wt% is added as the upper limit.
【００２１】また、２次加工脆性の改善を目的に、Ｂを
添加することが有効である。しかし、このＢ添加量があ
まりに高いと鋼の再結晶温度を上昇させ、鋼を硬質化す
るため、0.002 wt％以下含有させることが望ましい。Further, it is effective to add B for the purpose of improving the secondary working brittleness. However, if the amount of B added is too high, the recrystallization temperature of the steel is raised and the steel is hardened, so it is desirable to contain 0.002 wt% or less.
【００２２】同様に、冷延鋼板の、特に深絞り性を向上
するには、冷延鋼板を700 ℃〜Ａc3点で１sec 以上の連
続焼鈍を施すことが有効である。すなわち、700 ℃以上
の温度域で１sec 以上の均熱処理にて再結晶化をはかる
ことが、深絞り性の向上に有効である。一方、Ａc3点
（約920 ℃）をこえると深絞り性が急激に悪化するた
め、Ａc3点以下とする。Similarly, in order to improve the deep drawing property of the cold-rolled steel sheet, it is effective to subject the cold-rolled steel sheet to continuous annealing at 700 ° C. to Ac 3 point for 1 second or more. That is, it is effective to improve the deep drawability by performing recrystallization in a temperature range of 700 ° C. or higher by soaking for 1 second or longer. On the other hand, if the temperature exceeds the A c3 point (about 920 ° C.), the deep drawability deteriorates rapidly, so the A c3 point is set.
【００２３】[0023]
【実施例】転炉で 280ｔの溶銑をＣ：0.02〜0.1 wt％程
度に粗脱炭しかつMn量を調整した溶鋼を取鍋に出鋼し、
次いでＲＨ式真空脱ガス装置によりＣ：0.005 wt％以下
の極低炭素域までの脱炭処理を施した。その後、溶鋼中
にAl、Si、次いでTiの順に添加して段階的な脱酸処理を
行い、表１に示す各種成分の溶鋼を溶製した。同様に、
さらにNb, （Ｂ）を添加した溶鋼も溶製した。その後、
タンディッシュ内溶鋼重量が60ｔの２ストランドスラブ
連続鋳造機により、断面寸法220 ×1650mm幅のスラブ
に、溶鋼加熱度15〜30℃および鋳造速度2.5 ｍ／min で
鋳造した。なお、タンディッシュノズルの耐火物の材質
には、Al 2O3 −グラファイト質のものを使用した。連続
鋳造後、ノズル耐火物内の介在物の付着状況を調査し
た。その結果を表１に併記する。[Example] In a converter, 280 tons of hot metal was added to C: 0.02 to 0.1 wt%
Coarse decarburization and adjusting the amount of Mn, the molten steel is tapped into a ladle.
Next, using an RH-type vacuum degasser, C: 0.005 wt% or less
Was subjected to decarburization treatment up to the extremely low carbon range. Then in molten steel
Al, Si, and then Ti in this order for stepwise deoxidation treatment.
Then, molten steel having various components shown in Table 1 was melted. Similarly,
Further, molten steel containing Nb, (B) was also melted. afterwards,
Two-strand slab with 60t molten steel in tundish
A slab with a cross-sectional dimension of 220 x 1650 mm width produced by a continuous casting machine
At a molten steel heating rate of 15 to 30 ° C and a casting speed of 2.5 m / min
Cast. The material of the refractory of the tundish nozzle
For Al TwoOThree-Used a graphite material. Continuous
After casting, investigate the adhesion of inclusions in the nozzle refractory
Was. The results are also shown in Table 1.
【００２４】その後、上記連続鋳造スラブを1200℃に再
加熱した後、900 ℃で熱間仕上圧延を行い、600 ℃で巻
き取った。その後、酸洗し80％の圧下率で冷間圧延を行
った。次いで、連続焼鈍炉にて700 ℃〜900 ℃で40sec
均熱し、引き続き0.5 ％の調質圧延を行った。かくして
得られた冷延板に溶融亜鉛めっきを施したのち、材料試
験および表面調査に供した。これら試験および調査結果
を、表２に示す。なお、表面状態の調査結果は、上記と
同様に指数で表示した。After that, the above continuously cast slab was reheated to 1200 ° C., then hot finish rolled at 900 ° C. and wound at 600 ° C. Then, it was pickled and cold-rolled at a reduction rate of 80%. Then, in a continuous annealing furnace at 700 ℃ ~ 900 ℃ for 40 seconds
After soaking, 0.5% temper rolling was carried out. The cold-rolled sheet thus obtained was subjected to hot dip galvanizing and then subjected to a material test and surface investigation. The results of these tests and surveys are shown in Table 2. In addition, the result of the surface condition survey was expressed by an index similar to the above.
【００２５】[0025]
【表１】 [Table 1]
【００２６】[0026]
【表２】 [Table 2]
【００２７】本発明に従う方法は、タンディッシュのノ
ズル閉塞がなく、しかも冷延鋼板の表面欠陥の発生が極
めて少ない上、材料特性にも優れることがわかる。It can be seen that the method according to the present invention does not cause nozzle clogging of the tundish, the occurrence of surface defects on the cold rolled steel sheet is extremely small, and the material properties are excellent.
【００２８】[0028]
【発明の効果】以上説明したように、本発明によれば、
連続鋳造時にタンディッシュのノズルからのガス吹き込
みを行うことなくノズル閉塞を防止を達成し、かくして
得られたスラブからは表面欠陥のない機械的特性にも優
れた冷延鋼板が製造できる。As described above, according to the present invention,
Nozzle blockage is prevented without blowing gas from a tundish nozzle during continuous casting, and a cold rolled steel sheet having no surface defects and excellent mechanical properties can be produced from the slab thus obtained.
【図１】溶鋼中のAl量とタンディッシュノズルへのAl2O
3 の付着量（指数）との関係を示す図である。Figure 1: Al content in molten steel and Al 2 O for the tundish nozzle
It is a figure which shows the relationship with the adhesion amount (index) of 3 .
【図２】溶鋼中のAl量と、冷延鋼板におけるAl2O3 クラ
スターに起因した表面欠陥の発生量（指数）との関係を
示す図である。FIG. 2 is a diagram showing a relationship between an amount of Al in molten steel and an amount (index) of surface defects caused by Al 2 O 3 clusters in a cold rolled steel sheet.
【図３】溶鋼中のTi量と連続鋳造鋳片の表層部のブロー
ホールの発生量（指数）との関係を示す図である。FIG. 3 is a diagram showing the relationship between the amount of Ti in molten steel and the amount of blowholes (index) generated in the surface layer of a continuously cast slab.
【図４】溶鋼中のTi量とTiO2およびTiN のノズル内壁へ
の付着量（指数）との関係を示す図である。FIG. 4 is a diagram showing the relationship between the amount of Ti in molten steel and the amount (index) of TiO 2 and TiN adhering to the inner wall of the nozzle.
【図５】溶鋼中のSi量と冷延鋼板の伸びとの関係を示す
図である。FIG. 5 is a diagram showing the relationship between the amount of Si in molten steel and the elongation of a cold rolled steel sheet.
Claims (1)
る脱炭処理後の溶鋼中に、Alおよび／またはSiを添加し
て半脱酸溶鋼とし、この半脱酸溶鋼中に、含Ti物質を添
加してさらに脱酸し、Al≦0.005 wt％、Si≦0.20wt％、
Ti：0.01〜0.10wt％を含有する溶鋼とすると共に、該溶
鋼中の介在物の主成分をTiとAlとの複合酸化物、TiとSi
との複合酸化物、もしくはTi, AlおよびSiの複合酸化物
とした溶鋼を溶製し、次いでこの溶鋼を連続鋳造し、そ
の後、熱間圧延および冷間圧延を経たのち、得られた冷
延鋼板を 700℃〜Ａc3点の温度域で連続焼鈍することを
特徴とする極低炭素冷延鋼板の製造方法。1. A decarburized molten steel containing C ≦ 0.005 wt% and Mn ≦ 1.0 wt% is added with Al and / or Si to form a semi-deoxidized molten steel. , Ti-containing substance was added to further deoxidize, Al ≦ 0.005 wt%, Si ≦ 0.20 wt%,
Ti: Molten steel containing 0.01 to 0.10 wt%, and the main component of inclusions in the molten steel is a composite oxide of Ti and Al, Ti and Si.
Melted molten steel that was made into a complex oxide with or a mixed oxide of Ti, Al and Si, and then continuously cast this molten steel, followed by hot rolling and cold rolling, and then the cold rolling obtained. A method for producing an ultra-low carbon cold-rolled steel sheet, which comprises continuously annealing a steel sheet in a temperature range of 700 ° C to Ac 3 points.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00777196A JP3422612B2 (en) | 1996-01-19 | 1996-01-19 | Manufacturing method of ultra low carbon cold rolled steel sheet |
| BR9700715A BR9700715A (en) | 1996-01-19 | 1997-01-17 | Method of producing steel with ultra-low carbon content |
| TW086100481A TW330213B (en) | 1996-01-19 | 1997-01-17 | Production of extra-low carbon cold-rolled steel sheet |
| CA002195369A CA2195369A1 (en) | 1996-01-19 | 1997-01-17 | Method of making ultra low-carbon steel |
| KR1019970001283A KR100233690B1 (en) | 1996-01-19 | 1997-01-17 | Method of making ultra low carbon steel |
| EP97100687A EP0785283A1 (en) | 1996-01-19 | 1997-01-17 | Method of making ultra low-carbon steel |
| US08/784,833 US5879479A (en) | 1996-01-19 | 1997-01-17 | Method of making ultra low-carbon steel |
| CN97102991A CN1048285C (en) | 1996-01-19 | 1997-01-19 | Method for making ultralow carbon cold-rolled steel plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00777196A JP3422612B2 (en) | 1996-01-19 | 1996-01-19 | Manufacturing method of ultra low carbon cold rolled steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09192804A true JPH09192804A (en) | 1997-07-29 |
| JP3422612B2 JP3422612B2 (en) | 2003-06-30 |
Family
ID=11674949
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00777196A Expired - Fee Related JP3422612B2 (en) | 1996-01-19 | 1996-01-19 | Manufacturing method of ultra low carbon cold rolled steel sheet |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5879479A (en) |
| EP (1) | EP0785283A1 (en) |
| JP (1) | JP3422612B2 (en) |
| KR (1) | KR100233690B1 (en) |
| CN (1) | CN1048285C (en) |
| BR (1) | BR9700715A (en) |
| CA (1) | CA2195369A1 (en) |
| TW (1) | TW330213B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999041421A1 (en) * | 1998-02-17 | 1999-08-19 | Nippon Steel Corporation | Steel for thin sheet excellent in workability and method for deoxidation thereof |
| KR100743367B1 (en) * | 2001-07-04 | 2007-07-26 | 주식회사 포스코 | Method of refining low nitrogen, low carbon stainless steel sheets having stabilized titanium |
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|---|---|---|---|---|
| TW408184B (en) * | 1997-09-29 | 2000-10-11 | Kawasaki Steel Co | Manufacturing method for producing Titanium killed steel with smooth surface texture |
| US5868875A (en) * | 1997-12-19 | 1999-02-09 | Armco Inc | Non-ridging ferritic chromium alloyed steel and method of making |
| US6855213B2 (en) | 1998-09-15 | 2005-02-15 | Armco Inc. | Non-ridging ferritic chromium alloyed steel |
| EP1029938A3 (en) * | 1999-02-18 | 2003-10-15 | Nippon Steel Corporation | Rolled steel having few inclusion defects |
| NL1013776C2 (en) * | 1999-06-04 | 2000-12-06 | Corus Staal Bv | Ultra Low Carbon steel and method for its manufacture. |
| WO2002048409A1 (en) * | 2000-12-13 | 2002-06-20 | Kawasaki Steel Corporation | Process for producing high-nitrogen ultralow-carbon steel |
| KR100554142B1 (en) * | 2001-12-07 | 2006-02-20 | 주식회사 포스코 | Refining process of invar steel |
| FR2833970B1 (en) * | 2001-12-24 | 2004-10-15 | Usinor | CARBON STEEL STEEL SEMI-PRODUCT AND METHODS OF MAKING SAME, AND STEEL STEEL PRODUCT OBTAINED FROM THIS SEMI-PRODUCT, IN PARTICULAR FOR GALVANIZATION |
| FR2853668A3 (en) * | 2003-04-08 | 2004-10-15 | Usinor | Cold-rolled thin sheet steel for packaging, e.g. for making beverage cans, has a low aluminum content and high silicon content and is annealed at low temperature |
| CN100368577C (en) * | 2005-12-29 | 2008-02-13 | 攀枝花钢铁(集团)公司 | Process for producing fine type steel crystal particle |
| CN102174683B (en) * | 2011-01-30 | 2012-10-10 | 首钢总公司 | Method for producing cold-rolling low-carbon aluminum killed steel with uniform through plate mechanical property |
| TWI515301B (en) * | 2012-03-08 | 2016-01-01 | 杰富意鋼鐵股份有限公司 | Method for manufacturing ultra low carbon steel by using vacuum-degassing system |
| CN109304367B (en) * | 2018-11-08 | 2021-01-15 | 瓯锟科技温州有限公司 | Titanium-steel-titanium composite board and preparation method thereof |
| CN111187874A (en) * | 2020-03-02 | 2020-05-22 | 马鞍山钢铁股份有限公司 | Production method for reducing pore defects of ultra-low carbon enamel steel casting blank with C less than or equal to 0.0030% |
| KR20230022213A (en) * | 2020-07-08 | 2023-02-14 | 제이에프이 스틸 가부시키가이샤 | Manufacturing method of ultra-low carbon steel products |
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|---|---|---|---|---|
| JPS6045689B2 (en) * | 1982-02-19 | 1985-10-11 | 川崎製鉄株式会社 | Method for manufacturing cold rolled steel sheet with excellent press formability |
| JPS6179745A (en) * | 1984-09-28 | 1986-04-23 | Nippon Steel Corp | Manufacture of steel material superior in welded joint heat affected zone toughness |
| DE3528782A1 (en) * | 1985-08-10 | 1987-02-19 | Hoesch Stahl Ag | METHOD FOR PRODUCING AN AGING-RESISTANT STRIP STEEL WITH HIGH COLD FORMABILITY |
| US5053194A (en) * | 1988-12-19 | 1991-10-01 | Kawasaki Steel Corporation | Formable thin steel sheets |
| WO1992014854A1 (en) * | 1991-02-20 | 1992-09-03 | Nippon Steel Corporation | Cold-rolled steel sheet and galvanized cold-rolled steel sheet which are excellent in formability and baking hardenability, and production thereof |
| JPH07268440A (en) * | 1994-03-28 | 1995-10-17 | Nippon Steel Corp | Deoxidizing method of molten steel |
-
1996
- 1996-01-19 JP JP00777196A patent/JP3422612B2/en not_active Expired - Fee Related
-
1997
- 1997-01-17 BR BR9700715A patent/BR9700715A/en not_active Application Discontinuation
- 1997-01-17 TW TW086100481A patent/TW330213B/en active
- 1997-01-17 US US08/784,833 patent/US5879479A/en not_active Expired - Lifetime
- 1997-01-17 EP EP97100687A patent/EP0785283A1/en not_active Ceased
- 1997-01-17 CA CA002195369A patent/CA2195369A1/en not_active Abandoned
- 1997-01-17 KR KR1019970001283A patent/KR100233690B1/en not_active IP Right Cessation
- 1997-01-19 CN CN97102991A patent/CN1048285C/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999041421A1 (en) * | 1998-02-17 | 1999-08-19 | Nippon Steel Corporation | Steel for thin sheet excellent in workability and method for deoxidation thereof |
| US6511553B1 (en) | 1998-02-17 | 2003-01-28 | Nippon Steel Corporation | Steel for steel excellent in workability and method of deoxidizing same |
| KR100743367B1 (en) * | 2001-07-04 | 2007-07-26 | 주식회사 포스코 | Method of refining low nitrogen, low carbon stainless steel sheets having stabilized titanium |
Also Published As
| Publication number | Publication date |
|---|---|
| KR100233690B1 (en) | 1999-12-01 |
| US5879479A (en) | 1999-03-09 |
| TW330213B (en) | 1998-04-21 |
| BR9700715A (en) | 1998-10-06 |
| EP0785283A1 (en) | 1997-07-23 |
| CN1167157A (en) | 1997-12-10 |
| CA2195369A1 (en) | 1997-07-20 |
| JP3422612B2 (en) | 2003-06-30 |
| KR970058805A (en) | 1997-08-12 |
| CN1048285C (en) | 2000-01-12 |
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